The differentiation of pulpal cells into odontoblasts during pulpal healing will be studied in two model systems with a view to developing a biological method of pulp capping. An in vitro model using enzymatically separated bovine pulp cells grown in monolayer initially and subsequently in a three dimensional cell plug system. Cells from various concentric regions of the bovine pulp will be stimulated to differentiate into preodontoblasts or odontoblasts and possibly form predentine and dentine, by biological 'materials' such as dentine, predentine, enamel, reduced enamel epithelium, and root sheath. Cells will be cultured against several inert surface variables: Millipore filter (0.45 micron and 0.1 micron, both sides of the filter), cellophane, Teflon, isobutyl cyanoacrylate, and paper. The surfaces will be modified as appropriate. The commonly used endodontic materials, suitably modified for in vitro experiments will also be investigated. Enzyme histochemical methods will be used to follow the differentiation of the cells involved. BIBLIOGRAPHIC REFERENCES: Miller, W.A., Everett, M.M., and Cramer, J.f. (1976) Growth of bovine pulp cells in monolayer culture. J. Endo. (Galley proofs: 12 Aug. 76). Everett, M.M and Miller, W.A. (Apr. 1976) Binding of phosphomolybdic acid to model substances. Histochemical society; Louisville, Kentucky.